Low-voltage circuit breaker with a capability of tripping quickly

ABSTRACT

This invention discloses a low-voltage circuit breaker with a capability of tripping quickly. Its main feature is that at least one of the side faces of the contact device provides an open flange which has an internal through hole, and the bottom of a rotating shaft disposed on the bottom part provides a stressed member. The stressed member receives the over-pressure airflow escaping from the open flange of the contact device to generate a force. The force is passed to the activating member by the rotating shaft and is magnified, then hits the latch quickly and makes a trip. An intermediate step is bypassed due to the force produced earlier, the force which is produced by the electromagnetism part in the heat energy and electromagnetic system, so that the low-voltage breaker can open quickly and reduces opening time greatly and improve the breaking capability.

FIELD OF THE INVENTION

This invention relates to a low-voltage circuit breaker with one-pole ormulti-pole, particularly to a low-voltage circuit breaker with acapability of tripping quickly.

DESCRIPTION OF THE RELATED ART

The conventional low-voltage circuit breaker includes a one-pole ormulti-pole contact device, an operating mechanism that can open or closethe brake, the heat energy and electromagnetic tripper that can takeaction when an over-loading and/or short-circuit occurs, and a bottompart, a base part and a casing which receive the contact device, theoperating mechanism and the tripper. As is well known, when a circuitbreaker is overloaded with high volume of current, the contact heads ofthe contact device would be affected by the electrical dynamic torepulse each other so that the current is limited, then theelectromagnetic part of the heat energy and electromagnetic tripper isactuated to quickly switch off the breaker and to protect the power lineand the equipment. In multi-pole circuit breakers, each pole may beimpacted by the short-circuit current, so it is necessary for each ofthem to have a capability of current-limiting and electromagneticallydisconnecting the circuit quickly. However, the conventional breaker cannot switch quickly only by mutual repulsion of the contact heads in thecontact system to limit the current and by the action of theelectromagnetic part of the heat energy and electromagnetic tripper fordisconnection, and always causes the disconnection capability of thebreaker for short circuit to reach saturation, thus it is difficult toenhance the switching capability.

A patent with the number ZL92111503.2 in China provides a low-voltagecircuit breaker with rapid disconnection capability, which uses the gaschamber to collect the high pressure gas generated by disconnecting thecurrent with contact heads, and to push the piston and drive the leverto hit the latch and disintegrate the four-lever structure of theoperating mechanism in the breaker so as to disconnect the switchrapidly. However, its structure and technique is complex and itsproduction cost is high.

SUMMARY OF THE INVENTION

Accordingly, an objective of the present invention is to provide alow-voltage circuit breaker with a capability of tripping quickly tosolve the problems in a conventional breaker, namely, that the breakingprotection capability tends to saturate and the breaking capability ishard to enhance.

In order to accomplish the above objective, the present inventionprovides a simple and effective solution: a circuit breaker comprising ahousing with a bottom part, a base part and a casing; a one-pole ormulti-pole contact device, an arc-extinguishing chamber witharc-extinguishing grid disposed in the contact device, the contact headsdisposed in the arc-extinguishing chamber can be disconnected under theforce of electrical repulsion generated when the current exceeds acertain value, thus limiting can limit the current; an operatingmechanism that can open and close the contact heads and, a heat energyand electromagnetic tripper and a rotating shaft that can drive theoperating mechanism in case of over loading and/or short-circuitsoccurs; wherein at least one of the side surfaces of the contact deviceprovides an open flange that is communicated to a chamber whereinhigh-pressure gas is produced and stored; and the rotating shaft isdisposed on a corresponding location of the bottom base. The rotatingshaft includes a stressed member mating with the open flange and anactivating member to actuate the tripper of the operating mechanism todisconnect the switch with torsion passed by the stressed member. Theactivating member is disposed corresponding to the latch.

When the low-voltage circuit breaker is impacted by a high volumecurrent, the contact heads are disconnected by the repulsive force, toproduce electric arc, and then to generate energy and impact, whereinmost of the energy and impact are consumed by the arc-extinguishinggrids, some of the energy and impact escape along the open flange of thecontact device. The stressed members receive the overpressure airflowthat flows from the open flange of the contact device. In this way, arotating force around the rotating shift is produced. The rotating forceis passed to and magnified by the activating member, then the activatingmember hits the latch quickly and makes a trip. Because the rotatingforce is produced earlier than the force which is produced by the heatenergy tripper and the electromagnetic part in the electromagneticsystem, and the intermediate step in which an electromagnetic force hitsthe tripping device by the adjusting lever and the bounce latch iseliminated, the low-voltage breaker can break the circuit early so as toreduce breaking time and greatly improve breaking capability. Bytheoretical analysis, this multi-pole low-voltage circuit breaker of thepresent invention can improve the breaking capability of theconventional breaker by 50%, which has been confirmed by experiment.

The lower end of the rotating shaft is disposed on a first supportmember on the bottom part and the upper end is pivoted on a secondsupport member. The second support member is mechanically connected tothe bottom part to keep the rotating shaft rotating flexibly.

A floating sensor member is jacketed within the open flange of thecontact device. There is a travel clearance in the axial directionbetween the sensor member and the open flange; the stressed member is ina wing-shape and its stressed surface is perpendicular to the axis ofthe open flange. The sensor member receives the airflow escaping fromthe open flange of the contact device and flows out, hitting therotating wing-shape pieces, which produces a rotating force around therotating shaft. This rotating force is passed on to the activatingmember and magnified, then the activating member hits the latch quicklyand makes a trip. The angle of rotation for the rotating shaft isconfined by the location of its installation between the wing-shapedpieces and the contact device. The sensor member is confined within theopen flange after finishing its working travel to keep the gas in thecontact device from leaking. The exterior surface of the open flange isin a cone-shape, such shape cannot only ensure the strength of theflange, but also save material.

As another embodiment of this invention, the exterior surface of theopen flange is in cylindrical shape; the stressed member is in acup-shape and mated with the open flange, and the mating distancebetween them is longer than the travel of the stressed member. If therotating shaft rotates under a heavy airflow, the cup-shaped stressedmember should not disengage from the open flange of the contact device.This prevent the gas from circulating between the adjacent contactdevices to induce short circuit or the gas of one single pole escape todestroy the bottom part, the base part and the casing, etc.

The rotating shaft, the activating member and the stressed member can bedesigned into an integrated structure or a structure with parts thatcould be assembled. The former structure has higher rigidity and easy toproduce. This mechanism is arranged between the adjacent contact devicesor on one side of one single pole. The lower end and the middle parts ofthe rotating shaft have support to keep it rotating smoothly andquickly. The rotating shaft has a return spring that can move backquickly when the gas-flow hits the latch and make a trip so as toimplement the next over-loading interruption. The spring can be atorsion spring, a pulling spring or a press spring. In a low-voltagecircuit breaker, a single rotating shaft may be arranged for a singlepole breaker. For a multi-pole breaker, in order to improve theinterrupting capability for each pole, such quick trip mechanism shouldalso be arranged between every two adjacent pole contact devices, sothat when the number of the pole of the multi-pole breaker is n, thenumber of the quick trip mechanism is n−1. Therefore, each quick tripmechanism can drive the tripper to make a trip, and achieve the purposeof allowing the low-voltage circuit breaker to break quickly and toprotect the circuit and the equipment.

In the multi-pole breaker, the stressed member of the rotating-hit quicktrip mechanism is, preferably, a pair, facing toward the open flange ofthe adjacent contact device, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, the present invention will be described with reference tothe accompanying drawings and embodiments:

FIG. 1 is a structural schematic view of an embodiment of a low-voltagecircuit breaker of the present invention.

FIG. 2 is an amplified perspective view of the rotating shaft withdouble wing-shape pieces, a main-body rotating shaft and activatingmember.

FIG. 3 is a structural schematic view of the tripping device of thesensor member and the open flange.

FIG. 4 is an inner structural schematic view of the multi-pole contactdevice.

FIG. 5 is a structural schematic view of the heat energy andelectromagnetic tripper.

FIG. 6 is a perspective view of the base part with the casing.

FIG. 7 is an amplified perspective view of the rotating shaft with asingle wing-shape piece, main-body rotating shaft and activating member.

FIG. 8 is a structural schematic view of another embodiment of thelow-voltage circuit breaker of the present invention.

FIG. 9 is an amplified perspective view of the rotating shaft with apair of cup-shape stressed members.

FIG. 10 is an amplified perspective view of the rotating shaft with asingle cup-shape stressed member.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-6, the low-voltage circuit breaker has a housingwith a bottom part 4, a base part 17 and a casing 18, and includes atriple-pole contact device 5 arranged side by side; twoarc-extinguishing grid chambers 14; two pairs of contact heads 12, 13installed in the arc-extinguishing grid chamber 14, which will beseparated by the electrical repulsion force generated when the currentexceeds a certain value to limit the current; an operating mechanism 1that can open and close the contact heads; a heat energy andelectromagnetic tripper 15 that can drive the operating mechanism 1 whenan over-loading and/or short circuit occurs; and a rotating shaft 8,wherein the lower end of the rotating shaft 8 is disposed on a firstsupport member 32 of the bottom part 4, the upper end of the rotatingshaft 8 is pivoted on a second support member 33 which is mechanicallyconnected to the bottom part 4. The rotating shaft 8 receives the forcecoming from the contact device 5 by a pair of wing-shaped piecesdisposed on the bottom end thereof to generate torsion, and then drivethe tripping device 23 of the operating mechanism 1 when the torsionreaches a certain value.

The top of the rotating shaft 8 provides an activating member 9. Therotating shaft 8, the activating member 9 and the wing-shaped pieces 30are molded into an integrated structure made from plastic. Theactivating member 9 is disposed correspondingly to a latch 7. On bothsides of the middle contact device 5, there are in-pass open flanges 6,but the contact devices 5 on the two sides only have the open flange 6toward their inner sides. The open flange 6 is communicated with achamber 34 where high-pressure gas can be produced and stored. Theexterior surface 27 of the open flange 6 is in a cone-shape. A sensormember 29 is a cylinder with a taper or half ball head, jacketed in theopen flange 6 and opposite to the wing-shaped pieces 30. Each stressedsurface 20 of the wing-shaped pieces 30 is perpendicular to the axes ofthe open flange 6. The sensor member 29 floats in the open flange 6 andcan move a certain distance in the axial direction. The sensor member 29was confined and can only move a certain distance due to the restrictionof the rotating wing-shaped pieces 30 when the sensor member 29 hits therotating wing-shaped pieces 30. The sensor member 29 receives theairflow escaping from the open flange 6 of the contact device 5 andsprings out to hit the rotating wing-shaped pieces 30 and produce arotating force around the rotating shaft 8. This force is passed on tothe activating member 9 and magnified, then the activating member hitsthe latch 7 quickly and makes a trip. A restoration spring 3 makes themain body of the rotating shaft 8 restore to its original position. Atthe same time, the sensor member 29 recovers to its original position toimplement interruption when the next short circuit occurs.

The embodiment showed in FIG. 7 is an improvement based on the aboveembodiment. The difference is that there is a single wing-shaped piece30 disposed on the rotating shaft. In this way, each contact device 5provides an open flange 6 at the same side correspondingly to thewing-shaped piece 30. Similarly, this structure is more suitable for thesingle-pole breaker.

Another embodiment is showed in FIG. 8 and FIG. 9. The difference fromthe embodiment in FIG. 1 is that a stressed member 10 is disposed on thebottom of the rotating shaft and is a cup-shape. The exterior surface 27of the open flange 6 of the contact device 5 is in a cylindrical shape.This cup-shaped stressed member 10 covers over the open flange 6. Amatting distance between them is longer than the working distance of thestressed member 10.

When the low-voltage circuit breaker is impacted by a high volume ofcurrent, the contact heads 12, 13 are separated by the repulsion forceto produce an electric arc and then generate energy and impact. Most ofthe energy and impact are consumed by the arc-extinguishing gridtherein. Some of the energy and impact escape along the open flange 6 ofthe contact device 5. The cup-shaped stressed members 10 on the left andright receive the over-pressure airflow escaping from the open flanges 6of the contact devices 5 of the two adjacent poles. A rotating forcearound the rotating shaft is produced, which is passed on to theactivating member 9 on the top of the rotating shaft and magnified tohit the latch quickly and drive the latch to rotate around the shaftanticlockwise, then make a trip. Because the rotating force is producedearlier than the force which is produced by the electromagnetic part inthe heat energy and electromagnetic system, and the intermediate step inwhich an electromagnetic force hits the tripping device 23 by theadjusting lever 16 and the bounce latch 22 is eliminated, thelow-voltage circuit breaker can break the circuit quickly, and thebreaking capability is greatly enhanced. The embodiment showed in FIG.10 is an improvement based on the above embodiment. The difference isthat there is a single cup-shaped stressed member 10 of the rotatingshaft. In this way, each contact device 5 provides an open flange 6 atthe same side relative to the cup-shaped stressed member 10. Thisstructure is more suitable for the breaker with a single pole.

1. A low-voltage circuit breaker with a capability of tripping quickly,having a housing with a bottom part, a base part and a casing,comprising: one-pole or multi-pole contact device with anarc-extinguishing grid chamber disposed therein, contact heads installedin the arc-extinguishing chamber adapted to be separated by theelectrically operated repulsion force generated when an electricalcurrent exceeds a certain value to limit the current; an operatingmechanism that can disconnect and close the contact heads, a heat energyand electromagnetic tripper that can drive the operating mechanism whenan overloading and/or short-circuit occurs; and a rotating shaft;wherein at least one side face of the contact device provides an openflange that is connected to a chamber where high-pressure gas isproduced and stored; and the rotating shaft is disposed on the bottombase; the rotating shaft containing stressed members arrangedcorrespondingly to the open flange and an activating member that isadapted to activate a tripping device of the operating mechanism to makea trip with the rotating force passed on by the stressed members.
 2. Thebreaker according to claim 1, wherein the lower end of the rotatingshaft is disposed on a first supporting member of the bottom part, andthe upper end of the rotating shaft is pivoted on a second supportingmember, and the second supporting member is mechanically connected tothe bottom part.
 3. The breaker according to claim 2, wherein the openflange of the contact device contains a floating sensor member; therebeing a travel clearance in the axial direction between the sensormember and the open flange; the stressed member is in a wing-shape andits stressed surface is perpendicular to the axis of the open flange. 4.The breaker according to claim 3, wherein the exterior surface of theopen flange is in a cone-shape.
 5. The breaker according to claim 2,wherein the exterior surface of the open flange is cylinder-shaped; thestressed member is cup-shaped and jacketed over the open flange, and amating distance between them is longer than the working travel distanceof the stressed member.
 6. The breaker according to claim 1, wherein areturn spring is installed on the rotating shaft.
 7. The breakeraccording to claim 6, wherein the rotating shaft, the activating memberand the stressed members are formed as an integrated structure.